The present invention relates to a thin type solid electrolytic capacitor, a thin type transmission-line device, a composite electronic component integrating the capacitor or the transmission-line device with a semiconductor chip, and a method of producing the same.
Miniaturization, slimming, and sophistication in electronic devices have been progressing. These features are remarkable in portable devices. With this trend, electronic components mounted in these devices are increasingly required to be miniaturized, slimmed, and sophisticated.
In these circumstances, miniaturization and slimming not only in semiconductor components but also in passive components, especially in solid electrolytic capacitors and transmission-line devices, which are used for decoupling a power supply circuit, have also been increasingly demanded.
In this trend, miniaturization is also under way in a composite component which combines a semiconductor component with these passive components. In particular, since a solid electrolytic capacitor and a transmission-line device have a high capacitance as compared with that of a ceramic capacitor and the like, an excellent decoupling effect can be expected when they are combined with a semiconductor chip.
Conventionally, a surface-mounted type solid electrolytic capacitor is generally covered with mold resin package. FIG. 1 illustrates a sectional view of such a conventional resin-molded type solid electrolytic capacitor.
Referring to FIG. 1, a resin-molded type solid electrolytic capacitor 701 is composed of an anode body 1 which is a plate or foil of a valve action metal such as aluminum, niobium, tantalum, or alloys thereof serving as a base metal. The surface of the base metal is enlarged, and the enlarged surface of the base metal is covered by a dielectric layer, consisting of an oxide of the base metal. The capacitor also comprises a resist layer 2 which defines two sections, and a cathode conducting layer 3 which covers a major portion of the anode body 1. The capacitor further includes an anode terminal 71 which is firmly fixed to the portion of the anode body 1 which is not covered with the cathode conducting layer 3, a cathode terminal 81 which is firmly fixed to the cathode conducting layer 3, and a mold resin package 91. However, the capacitor is not thin enough due to the thickness of the mold resin necessary for molding.
Another structure for slimming solid electrolytic capacitors is disclosed in Japanese Patent laid-open No. 2003-249418. FIG. 2 shows a sectional view of a conventional thin solid electrolytic capacitor disclosed in it.
Referring to FIG. 2, a thin solid electrolytic capacitor 702 comprises an anode terminal 72 fixed to an anode body 1, a cathode terminal 82 fixed to a cathode conducting layer 3, a metal plate 92 covering the cathode conducting layer 3, and an insulating part 93 covered with the metal plate 92. The whole thickness can be reduced as the mold resin package is removed. However, further thinning is difficult because of the thickness of the metal plate necessary for handling.
To attain miniaturization of a composite electronic component built with a semiconductor component, a solid electrolytic capacitor is required to be reduced to a thickness of, for example, not more than 0.3 mm, which is as thin as that of a semiconductor chip.